I've had a 1991 300SE for just over 4 months now and I've gotten over the fact that she won't start on the first firing 9 out of 10 times. Now, though, I face what I think is a bigger problem. My coolant resevoir looks like it is filled with peanut butter. The short history is that I had a factory valve job done 2months ago so I thought that maybe the engine was pushing through residual from that so I decided and to have it flushed. The factory shop agreed with my theory then flushed it, twice they tell me. It looked good for a day and then the next day damn, SKIPPY.

So a few of questions I would greatly appreciate thoughts on:

1) Is my theory close to correct or is there a larger issue to worry about?
2) Is there a fix for this?
3) How damaging is this to my engine and maybe the radiator in particular?
(Bonus Question: Is there a standing record for the most money thrown into one of these 126s? I know I'm at 3 times what I paid for it already.)

Thanks and Cheers.

 

I think your oil is getting into the cooling system. The headgasket has failed or was not installed properly.

 

I agree. It doesn't sound like it is running right,, but hard to tell with out enough information. Have you done a compression check, Pressure cooling system check?

Also if they flushed but didn't pull the thermostat and did a pressure flush, they didn't do much. I had a 77 Olds. bought new that rusted freeze plugs at 14,000 miles. Factory said tough (umhh where is oldsmobile now?). I changed the freeze plugs took it to radiator shop that pulled the thermostate and pressure reverse flushed. The system was like new. It sounds like you didn't get much of a flush. I would take it for a reverse pressure flush if anyone can do that anymore.

Now for starting, If it isn't starting right you have another issue. If it is cranking slowly to start you could just have the timing too far advanced. It is also possible not getting enough fuel for enrichment. You didn't mention hot or cold start difficulty.

So there is a lot to do to solve this but it can be solved. It could be a bad gasket job but I would do some other checks first, It might not even be associated with the head job.

Jim

 

make sure its not reddish in color- once in a while a trans cooler can give it up and share fluid w/ the cooling system. more likely a headgasket though.

 

Thanks for the responses so far. Whatever I know about cars I've figured out myself with common sense which is to say not much. Here's a list of everything I've had done to the car, engine/transmission-wise:

"Major Premium Service"
>Change oil and filter
>Replace oil filter
>Replace spark plugs
>Install premium engine and fuel treatment
>Complete transmission flush and
>Install ATF treatment
>Complete cooling system flush and install cooling system treatment
>Multi point inspection

(Replaced muffler, pipe, hanger)

After discussing the starting issue with them, the shop said after diagnostic that there were dirty valves and the cold start valve might need replacement. A head gasket reseal was needed and if the head was warped it was going to cost more - it wasn't. So:

>Headgasket and valve job - new valve guides, valve stem
R&R cylinder head, clean contaminated coolant out
(work done at separate machine shop)
>Replace engine mounts
>New fuel pump, filter, metal lines, hollow screw, seal ring

2 months later after noticing the coolant condition I took her in again, this was the shop's response: "We just did coolant flush in Jan with headgasket repair, check out residual oil from headgasket repair, perform coolant flush, add anti freeze. test drive OK.

Then the problem is there again not a day or two later. I don't notice the engine temp rocketing.

To answer the questions here, the starting problem is equally bad in cold or warm weather. 9 out of 10 times its takes 3 cranks and that 10th time I just hold the key in ignition position for a second and the engine fires and starts almost silently with zero tremor, real nice.

To the best of my knowledge I have not I've had a compression check or a pressure cooling check done.

The coolant does not have a reddish color.


Looking at this on paper myself the headgasket job that was completed outside the MB shop looks like it's standing out.

Thanks again for the interest and the info/suggestions. If what I've written here is not detailed enough, I'm more than willing to take detailed questions from here directly to the shop.

 

It sure sounds like they did not install the headgasket properly.

 

I failed to mention that I have a minor oil leak, a small pool of it on the pan underneath the engine. Not much reaches the ground, I noticed it only because we just moved into a new house that had a spotless driveway and I noticed a couple of oil drops.

The bad head gasket install does seems to be my best bet. I think the shop put the old one back on after the valve job and I've got a bad seal or it's just old and defective. Also, a friend told me to have them check the upper radiator hose. It's spongy instead of firm which he said is a sign to replace it, fwiw.

 

I see now.

I bet these people do not work on MB's regularily.

They should put a new head gasket in there. Not only that, they should also use new head bolts on your motor and use a very specific tightening sequence.

The radiator hose should be soft (it is rubber after all). A new one is soft. A old one will be hard and brittle.

 

I have had this problem recently on an engine I worked on. The engine was
a 102 in a 93 190e. I replaced the head gasket, flushed the system with
what I thought was an adequate flush. I ended up having to flush the system twice with a citric acid crystal solution used by MB before the coolant was
clean, even then there were remainders of that "peanut butter". Once that oil is in the system its damn hard to get out. Also your friends right, the oil
in the system breaks down the rubber hoses, makes them feel like you could
rip it in half easily, I recommend replacing them.

 

When oil gets in the cooling system, Mercedes has a special degreaser (part number 001 986 21 71). Use a 3% solution and run the engine for 15 minutes with heat set to high.

Citric acid is to remove hard deposits.

The OP did not have a failed headgasket to start with. I think the shop did a valve job but used the old head gasket. Then logic says they probably used the same head bolts. These are stretchy bolts and should be replaced with new ones. The old gasket and old bolts probably caused the oil to leak into the cooling system.

 

Took the car to the shop this morning. They say they did replace the head gasket and that usually it's tough to use an old one again after dismantling the engine. They're going to re-check installation then flush it again several times using the solution loubapache suggested during one of the flushes.

I'll update when I get word. No offense to enthusiasts but the C230 Sport they loaned me has the ride of a stagecoach.

 

its called a milkshake and you need to replace head gasket ,electric coolant pump, all coolant lines ,radiator ,flush heater core real good ,thats how to do it right to prevent any other cooling system failures in the future ,there might be 1 or 2 more things but start there ..............................

 

A year and a half later I thought I'd post a quick description of the solution here. I finally decided to stop taking my car to a dealer's shop and found a smaller shop that has been working on foreign cars for decades.

The shop confirmed that the head gasket was new but the bolts were the originals, here's the theory given to me. The installation looked decent enough when I brought the car to them but they told me it's possible that the bolts weren't initially tightened properly and remained that way for the car's first system flush. Then when I returned to have it flushed again it's likely that a dealer's mechanic checked the bolts, noticed they were not installed properly and tightened them, then continued with the further system flushes. By this point the damage was done and the inside of my radiator was coated with oil which caused the steady delivery of oil to my coolant resevoir. To make matters worse the dealer mechanic cracked the old radiator's coupling by overtightening the clamp.

The fix: Reinstall of the head gasket with new bolts. New radiator and hoses. System flush with Stoddard Solvent. Never a problem since.